Treat swift_willThrow(Typed) as not locking or performing allocation

Prior to throwing, Swift emits a call to `swift_willThrow(Typed)`,
which allows various diagnostic tools (such as debuggers and testing
libraries) to intercept errors at the point where they are initially
thrown.

Since `swift_willThrow(Typed)` can be hooked by arbitrary code at
runtime, there is no way for it to meet performance constraints like
@_noLocks or @_noAllocation. Therefore, in a function that has those
performance constraints specified, disable emission of the call to
`swift_willThrow(Typed)`.

Fixes rdar://140230684.

Author: DougGregor

stdlib/public/core/Availability.swift

@@ -40,6 +40,7 @@ import SwiftShims
 #if os(iOS) && !os(visionOS)
 @_effects(readnone)
 @_transparent
+@_noLocks
 public func _stdlib_isOSVersionAtLeast(
   _ major: Builtin.Word,
   _ minor: Builtin.Word,
@@ -51,6 +52,7 @@ public func _stdlib_isOSVersionAtLeast(
 @_semantics("availability.osversion")
 @_effects(readnone)
 @_unavailableInEmbedded
+@_noLocks
 public func _stdlib_isOSVersionAtLeast(
   _ major: Builtin.Word,
   _ minor: Builtin.Word,
@@ -63,6 +65,7 @@ public func _stdlib_isOSVersionAtLeast(
 @_semantics("availability.osversion")
 @_effects(readnone)
 @_alwaysEmitIntoClient
+@_noLocks
 public func _stdlib_isOSVersionAtLeast_AEIC(
   _ major: Builtin.Word,
   _ minor: Builtin.Word,
@@ -107,6 +110,7 @@ public func _stdlib_isOSVersionAtLeast_AEIC(
 @_semantics("availability.osversion")
 @_effects(readnone)
 @available(macOS 10.15, iOS 13.0, *)
+@_noLocks
 public func _stdlib_isVariantOSVersionAtLeast(
   _ major: Builtin.Word,
   _ minor: Builtin.Word,
@@ -149,6 +153,7 @@ public func _stdlib_isVariantOSVersionAtLeast(
 @_semantics("availability.osversion")
 @_effects(readnone)
 @_unavailableInEmbedded
+@_noLocks
 public func _stdlib_isOSVersionAtLeastOrVariantVersionAtLeast(
   _ major: Builtin.Word,
   _ minor: Builtin.Word,

stdlib/public/core/ErrorType.swift

@@ -181,6 +181,7 @@ public func _bridgeErrorToNSError(_ error: __owned Error) -> AnyObject
 @_silgen_name("swift_willThrowTypedImpl")
 @available(SwiftStdlib 6.0, *)
 @usableFromInline
+@_noLocks
 func _willThrowTypedImpl<E: Error>(_ error: E)
 
 #if !$Embedded

test/SILOptimizer/performance-annotations.swift

@@ -125,6 +125,37 @@ func testCatch(_ b: Bool) throws -> Int? {
   }
 }
 
+enum ErrorEnum: Error {
+  case failed
+  case tryAgain
+}
+
+@_noLocks
+func concreteError(_ b: Bool) throws(ErrorEnum) -> Int {
+  if b {
+    return 28
+  }
+
+  throw .tryAgain
+}
+
+func concreteErrorOther(_ b: Bool) throws(ErrorEnum) -> Int {
+  if b {
+    return 28
+  }
+
+  throw .tryAgain
+}
+
+@_noLocks
+func testCatchConcrete(_ b: Bool) -> Int {
+  do {
+    return try concreteError(b) + concreteErrorOther(b)
+  } catch {
+    return 17
+  }
+}
+
 @_noLocks
 func testRecursion(_ i: Int) -> Int {
   if i > 0 {